Track the common VFS calls which do disk I/O, to help analyze the impact
of any changes to how database connections are used or setup.
BUG=698010
Review-Url: https://codereview.chromium.org/2727103003
Cr-Commit-Position: refs/heads/master@{#457099}

Chromium's SQLite was modified to propagate OSX Time-Machine exclusions
from the main database file to any associated journal files.
Re-implement this using a VFS which wraps the default VFS and makes the
check when opening journal files.
BUG=679941
Review-Url: https://codereview.chromium.org/2623083002
Cr-Commit-Position: refs/heads/master@{#445601}